Abstract

In previous publications we have reported on the reduction of semiconductor-laser FM noise with dispersive loss.^1–3 We have demonstrated linewidth reduction by a factor of 2000 by using a Doppler-free Faraday resonance from Cs vapor. We have also shown that the main contribution to the quenched linewidth comes from the I/f component of the frequency fluctuation’s noise spectrum Sφ(f). This is due to the fact that the laser linewidth is linearly proportional to the white-noise level, whereas it scales as the square root of the 1/f noise level. Using our optical-feedback scheme, we were able to quench both the 1/f and the white-noise components of the frequency fluctuation’s spectrum by almost 6 orders of magnitude. Because of the contribution of the 1/f noise, however, the linewidth was reduced by only 3 orders of magnitude from 20 MHz to 10 KHz.

© 1993 Optical Society of America